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Date:   Thu, 11 Feb 2021 10:30:16 +0100
From:   Greg Kroah-Hartman <gregkh@linuxfoundation.org>
To:     Gustavo Pimentel <Gustavo.Pimentel@synopsys.com>
Cc:     linux-doc@vger.kernel.org, linux-pci@vger.kernel.org,
        linux-kernel@vger.kernel.org,
        Derek Kiernan <derek.kiernan@xilinx.com>,
        Dragan Cvetic <dragan.cvetic@xilinx.com>,
        Arnd Bergmann <arnd@arndb.de>,
        Andrew Morton <akpm@linux-foundation.org>,
        Jonathan Corbet <corbet@lwn.net>,
        Bjorn Helgaas <bhelgaas@google.com>
Subject: Re: [PATCH v5 1/6] misc: Add Synopsys DesignWare xData IP driver
Message-ID: <YCT5KDnAWex8fvbz@kroah.com>
References: <cover.1613034397.git.gustavo.pimentel@synopsys.com>
 <02835da8fc8c9293fecbe666a8db3fb79276fdde.1613034397.git.gustavo.pimentel@synopsys.com>
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On Thu, Feb 11, 2021 at 10:08:38AM +0100, Gustavo Pimentel wrote:
> +static ssize_t write_show(struct device *dev, struct device_attribute *attr,
> +			  char *buf)
> +{
> +	struct pci_dev *pdev = to_pci_dev(dev);
> +	struct dw_xdata *dw = pci_get_drvdata(pdev);
> +	u64 rate;
> +
> +	mutex_lock(&dw->mutex);
> +	dw_xdata_perf(dw, &rate, true);
> +	mutex_unlock(&dw->mutex);
> +
> +	return sysfs_emit(buf, "%llu MB/s\n", rate);

Do not put units in a sysfs file, that should be in the documentation,
otherwise this forces userspace to "parse" the units which is a mess.

Same for the other sysfs file.

And why do you need a lock for this show function?

thanks,

greg k-h